In: Statistics and Probability
Confidence Intervals (Proportions)
1 Find the margin of error and 95% confidence interval for the following surveys. Round all answers to 2 decimal places.
(a) A survey of 500 people finds that 56% plan to vote for Smith for governor.
Margin of Error (as a percentage):
Confidence Interval: % to %
(b) A survey of 1500 people finds that 47% support stricter penalties for child abuse.
Margin of Error (as a percentage):
Confidence Interval: % to %
2 Assume that a sample is used to estimate a population proportion p. Find the 99% confidence interval for a sample of size 185 with 45 successes. Enter your answer as an open-interval (i.e., parentheses) using decimals (not percents) accurate to three decimal places.
3 Assume that a sample is used to estimate a population proportion p. Find the 98% confidence interval for a sample of size 386 with 38% successes. Enter your answer as an open-interval (i.e., parentheses) using decimals (not percents) accurate to three decimal places.
4 Assume that a sample is used to estimate a population
proportion p. Find the 95% confidence interval for a
sample of size 347 with 25% successes. Enter your answer as a
tri-linear inequality using decimals (not percents) accurate to
three decimal places.
Note : allowed to solve only 1 question per
post
Confidence Intervals (Proportions)
1 Find the margin of error and 95% confidence interval for the following surveys. Round all answers to 2 decimal places.
(a) A survey of 500 people finds that 56% plan to vote for Smith for governor.
Margin of Error (as a percentage):4.35%
Confidence Interval: 51.65% to 60.35%
(b) A survey of 1500 people finds that 47% support stricter penalties for child abuse.
Margin of Error (as a percentage):2.53%
Confidence Interval: (44.47% to 49.53%)